Last Updated on May 10, 2025 by Kevin Chen
The activated sludge system plays a vital role in wastewater treatment, and dissolved oxygen (DO) is one of the most critical factors affecting its performance. With over 16 years of expertise in the water treatment industry and specialized knowledge in MBR processes, we understand that proper DO control ensures optimal treatment efficiency, reduces operational costs, and improves system stability.
What Is Dissolved Oxygen (DO)?
Dissolved Oxygen (DO) refers to the amount of oxygen dissolved in water. It is vital for aquatic organisms’ survival and microbial metabolism in biological wastewater treatment systems.
DO levels in water are influenced by factors such as temperature, pressure, salinity, and water flow rate:
- Higher temperatures → lower DO solubility
- Higher salinity → lower DO
- Faster water flow → higher DO
Maintaining appropriate DO levels is essential to supporting microbial activity and ensuring the efficient degradation of organic pollutants in wastewater treatment systems.
What Are the Negative Effects of Excessive DO?
While sufficient oxygen is crucial for aerobic microorganisms, excessive DO can negatively impact biological treatment processes, especially in activated sludge systems:
- Inhibits microbial growth: High DO levels disrupt the internal balance of microorganisms, suppressing metabolism and reducing microbial populations.
- Alters metabolic pathways: Microbes may favor oxygen as the primary electron acceptor under high DO conditions, shifting from typical aerobic respiration to less efficient degradation pathways.
- Reduces organic degradation efficiency: Disrupted microbial communities result in poor organic matter breakdown and lower overall treatment efficiency.
In MBR systems, high DO may also influence membrane fouling behavior, increasing maintenance frequency and operating costs.
How to Prevent Excessive DO?
To ensure stable and efficient system performance, the following preventative measures can help control DO levels:
- ✅ Design low-oxygen zones: Creating low-DO areas at the inlet reduces overall oxygen levels in the system.
- ✅ Use dispersed aeration: Distribute oxygen evenly throughout the reactor to avoid localized over-oxygenation.
- ✅ Reduce aeration frequency: Limit unnecessary aeration to control DO levels and lower energy consumption.
How to Control Excessive Dissolved Oxygen?
If high DO levels have already become an issue in your system, we recommend implementing the following strategies:
- Install real-time DO monitoring: Use automated sensors and monitoring platforms to track DO levels at critical points and respond in real-time.
- Optimize aeration: Adjust aeration rates based on influent load to avoid excessive oxygen supply.
- Modify sludge return ratios: Reducing the sludge recirculation rate can increase aeration time and improve denitrification while preventing oxygen oversupply.
- Upgrade aeration equipment: Enhance oxygen transfer efficiency with more effective equipment to maintain ideal DO levels.
- Train your staff: Improve operator knowledge of DO management and ensure proper use of monitoring and aeration systems.
- Adjust sludge management: Adjust the sludge handling system to maintain biological stability during DO control interventions.
What We Offer
As a leading manufacturer of premium MBR membrane products – Sperta, we offer solutions widely used in municipal, industrial, commercial, and water reuse projects. Our membranes offer:
- 0.03-micron pore size for high-efficiency filtration
- Superior mechanical strength and durability
- High flux and excellent fouling resistance
Beyond membrane supply, we provide technical consulting and system design recommendations to help you tackle challenges such as DO control and overall process optimization.
Interested in learning more about MBR solutions and DO management strategies? Contact us or reach out via email for personalized support.
